1. Field of the Invention
The invention relates to an image recording apparatus useful in a video camera, a still camera, or the like which records a video signal from, for example, an imaging device having an expanded range of the amount of incident light, on a record medium, and also to an image reproducing apparatus which, when a video signal is reproduced from a medium on which the video signal is recorded by the image recording apparatus and then output, adjusts the luminance of the video signal in accordance with, for example, instructions from the user.
2. Description of the Related Art
Conventionally, a CCD which is used in a video camera or a still camera has a narrow dynamic range. Therefore, the illuminance range to be imaged is adjusted to an optimum one by controlling the amount of light incident on the CCD by means of a mechanical aperture while seeing an image of an object, or by controlling the period of accumulating signal charges by means of an electronic shutter. A video signal is obtained with adjusting the illuminance range in an optimum manner by means of the aperture or the electronic shutter, and then recorded on a medium such as a tape or a disk.
FIG. 28 shows an imaging method in the prior art. As shown in FIG. 28, the object illuminance in outdoors where the sun shines is different from that in a dark room by the factor of 100 to 1,000 times. To comply with this, when imaging is to be conducted in a dark room, the size of the aperture is increased, and, when imaging is to be conducted in bright outdoors, the size of the aperture is reduced, thereby obtaining an optimum illuminance.
According to the prior art method, when there exist both a dark room and bright outdoors in an imaging area, however, it is impossible to set the aperture to be a size at which imaging can be simultaneously conducted on both the dark room and the bright outdoors. This produces a problem as discussed below. The case where the photographer places emphasis on the inside of a room and takes an image to record it on a record medium with setting the aperture so as to correspond to the dark room will be considered. When the record medium is thereafter subjected to reproduction and the image is observed on a display apparatus, the portion of the image which corresponds to the outdoors appears as whiteout. Even when the observer wishes to see the outdoor portion, therefore, it is impossible to see the outdoor portion.
In contrast, in the case where an image is taken and recorded with setting the aperture so as to correspond to the bright outdoors, even when the observer wishes to see the room portion in reproduction, it is impossible to see the room portion because the room portion appears as blackout.
As seen from the above, in the prior art, only an image in which the object illuminance range is restricted can be recorded, thereby producing a problem in that it is impossible to see a portion in which the object illuminance in reproduction is largely different from that in imaging.
In order to attain the object, for example, the image recording apparatus of the invention comprises: imaging means for obtaining two video signals of different signal charge accumulation periods, in a given signal charge accumulation period which is represented by a field or a frame of a video signal; and means for separately recording the two video signals on a record medium, or means for selecting or correcting the two video signals for each predetermined number of pixels and then recording the video signals.
For example, the image reproducing apparatus of the invention comprises: video signal reproducing means for reproducing two video signals which have different signal charge accumulation periods and which are recorded on an image record medium separately or with being selected or corrected for each predetermined number of pixels; object illuminance range designating means for designating an object illuminance range which is to be displayed or output, or region designating means for designating a region for an image; and level converting means for converting a luminance level of a reproduced video signal.
According to the image recording apparatus of the invention having the above-mentioned configuration, for example, the imaging means for obtaining two video signals of different signal charge accumulation periods obtains, in a standard charge accumulation period, a video signal produced by imaging an object of a standard illuminance, and, in a charge accumulation period which is shorter than the standard period, a video signal produced by imaging an object of a high illuminance. The two obtained video signals are recorded on a record medium by video signal recording medium as they are, with being selected for each pixel, or with being corrected with each other, whereby a video signal of an object having a wide luminance distribution can be recorded.
According to the image reproducing apparatus of the invention, for example, video signals of the standard illuminance and the high illuminance are reproduced from a record medium, and the luminance level of a video signal which is indicated by a user through the object illuminance range designating means or the region designating means is converted by the level converting means into a luminance level which is suitable for a video signal outputting apparatus, thereby allowing portions which are largely different in object illuminance, to be selectively displayed or output in reproduction.
The first invention is an image recording apparatus which comprises plural imaging means which have different signal charge accumulation periods in one field or one frame, and recording means for recording a whole or a part of plural video signals obtained in the signal accumulation periods, on a predetermined record medium.
The second invention is an image recording apparatus according to said first invention,
wherein said recording means records a whole of the plural video signals on the record medium.
The third invention is an image recording apparatus according to said first invention,
wherein said apparatus further comprises selecting means for selecting one of the plural video signals output from said imaging means, on the basis of a predetermined criterion, and said recording means records the selected video signal.
The 4th invention is an image recording apparatus according to said third invention,
wherein the plural video signals which have different signal charge accumulation periods are two kinds of video signals or first and second video signals, the first video signal being longer in signal charge accumulation period than the second video signal, and,
in the selection of one of the video signals on the basis of the predetermined criterion, when a value of the first video signal is smaller than a predetermined threshold, the first video signal is selected, and, when the value of the first video signal is not smaller than the threshold, the second video signal is selected.
The 5th invention is an image recording apparatus according to said 4th invention,
wherein said apparatus further comprises identification information adding means for adding an identification information to the selected video signal, the identification information indicating which one of the two kinds of video signals is selected by said selecting means as the one video signal.
The 6th invention is an image recording apparatus according to said 4th invention,
wherein said selecting means comprises correcting means for, at least when the second video signal is to be selected, correcting the second video signal to be selected with using the second video signal and the threshold, and outputting the corrected second video signal.
The 7th invention is an image recording apparatus according to said 6th invention,
wherein said recording means comprises parameter recording means for recording a parameter which is used in the correction by said correcting means, on the record medium.
The 8th invention is an image recording apparatus according to said 6th invention,
wherein said recording means comprises parameter multiplexing means for recording a parameter which is used in the correction by said correcting means, with being multiplexed with the second video signal, on the record medium.
The 9th invention is an image reproducing apparatus which comprises:
reading means for reading out plural video signals which have different signal charge accumulation periods and are recorded on the record medium by said image recording apparatus according to said second invention;
selecting/outputting means for selecting one of the plural read out video signals, on the basis of a predetermined criterion, and outputting the selected video signal;
image displaying/outputting means for displaying or outputting an image with using the selected signal; and
object illuminance range designating means for designating an object illuminance range which is to be reproduced by said displaying/outputting means,
wherein the selected video signal is to be displayed or output by said image displaying/outputting means, at least in the designated object illuminance range.
The 10th invention is an image reproducing apparatus according to said 9th invention,
wherein said apparatus further comprises luminance level changing means for, when a luminance level of the selected signal in the designated object illuminance range exceeds a maximum limit of said image displaying/outputting means, changing the luminance level of the selected signal in the object illuminance range so as to become lower than the maximum limit.
The 11th invention is an image reproducing apparatus which comprises:
reading means for reading out plural video signals which have different signal charge accumulation periods and which are recorded on the record medium by said image recording apparatus according to said third invention;
image displaying/outputting means for displaying or outputting an image with using the read out signal; and
object illuminance range designating means for designating an object illuminance range which is to be reproduced by said displaying/outputting means,
wherein the read out signal is to be displayed or output by said image displaying/outputting means, at least in the designated object illuminance range.
The 12th invention is an image reproducing apparatus according to said 11th invention,
wherein said apparatus further comprises luminance level changing means for, when a luminance level of the read out signal in the designated object illuminance range exceeds a maximum limit of said image displaying outputting means, changing the luminance level of the read out signal in the object illuminance range so as to become lower than the maximum limit.
The 13th invention is an image reproducing apparatus which comprises:
reading means for reading out plural video signals which have different signal charge accumulation periods and which are recorded on the record medium by said image recording apparatus according to said second invention;
selecting/outputting means for selecting one of the plural read out video signals, on the basis of a predetermined criterion, and outputting the selected video signal;
image displaying(outputting means for displaying or outputting an image with using the selected signal;
region designating means for designating a predetermined region in an image region which can be subjected to the display or the output in said displaying/outputting means;
calculating means for calculating distribution of the number of pixels in the designated region with respect to a luminance; and
object illuminance range determining means for, with using a result of the calculation, determining an object illuminance range which is to be reproduced by said displaying/outputting means, in the designated region,
wherein a signal in the designated region is to be subjected to the display or the output by said image displaying/outputting means, in the determined object illuminance range.
The 14th invention is an image reproducing apparatus according to said 13th invention,
wherein said apparatus further comprises luminance level changing means for, when a luminance level of a signal in the designated region in the determined object illuminance range exceeds a maximum limit of said image displaying/outputting means, changing the luminance level of the signal in the designated range so as to become lower than the maximum limit.
The 15th invention is an image reproducing apparatus which comprises:
reading means for reading out plural video signals which have different signal charge accumulation periods and which are recorded on the record medium by said image recording apparatus according to said third invention;
image displaying/outputting means for displaying or outputting an image with using the read out signal;
region designating means for designating a predetermined region in an image region which can be subjected to the display or the output in said displaying/outputting means;
calculating means for calculating distribution of the number of pixels in the designated region with respect to a luminance; and
object illuminance range determining means for, with using a result of the calculation, determining an object illuminance range which is to be reproduced by said displaying/outputting means, in the designated region,
wherein a signal in the designated region is to be subjected to the display or the output by said image displaying/outputting means, in the determined object illuminance range.
The 16th invention is an image reproducing apparatus according to said 15th invention,
wherein said apparatus further comprises luminance level changing means for, when a luminance level of a signal in the designated region in the determined object illuminance range exceeds a maximum limit of said image displaying/outputting means, changing the illuminance level of the signal in the designated range so as to become lower than the maximum limit.
The 17th invention is an image reproducing apparatus according to said 11th or 15th invention,
wherein the plural video signals which have different signal charge accumulation periods are two kinds of video signals or first and second video signals, the first video signal being longer in signal charge accumulation period than the second video signal, and,
in the selection of one of the video signals on the basis of the predetermined criterion in said image recording apparatus, when a value of the first video signal is smaller than a predetermined threshold, the first video signal is selected, and, when the value of the first video signal is not smaller than the threshold, the second video signal is selected.
The 18th invention is an image reproducing apparatus according to said 17th invention,
wherein said image recording apparatus comprises identification information adding means for adding anidentification information to the selected video signal, the identification information indicating which one of the two kinds of video signals is selected by said selecting means as the one video signal.
The 19th invention is an image reproducing apparatus according to said 17th invention,
wherein said selecting means of said image recording apparatus comprises correcting means for, at least when the second video signal is to be selected, correcting the second video signal to be selected with using the second video signal and the threshold, and outputting the corrected second video signal.
The 20th invention is an image reproducing apparatus according to said 19th invention,
wherein said recording means of said image recording apparatus comprises parameter recording means for recording a parameter which is used in the correction by said correcting means, on the record medium.
The 21th invention is an image reproducing apparatus according to said 19th invention,
wherein said recording means of said image recording apparatus comprises parameter multiplexing means for recording a parameter which is used in the correction by said correcting means, with being multiplexed with the second video signal, on the record medium.
As a result, for example, the image recording apparatus of the invention records two video signals of the standard illuminance and a high illuminance which are obtained in different signal charge accumulation periods.
The image reproducing apparatus of the invention uses a video signal which is recorded by the image recording apparatus as described above.
According to the configuration described above, the invention can provide an image recording apparatus and an image reproducing apparatus which allow portions largely different in object illuminance to be observed in reproduction.
In other words, in the image reproducing apparatus of the invention, for example, the luminance level of a video signal read out from a record medium is converted in accordance with designation of the luminance range or region designation conducted by the user, whereby even portions which are largely different in object illuminance are allowed to be selectively displayed or output in reproduction.